Transdermal analyte sensor assembly and methods of using the same

ABSTRACT

A transdermal test sensor assembly adapted to determine an analyte concentration of a fluid sample is disclosed. The assembly comprises a sensor support including at least one reservoir adapted to hold a liquid. The assembly further comprises a test sensor being coupled to the sensor support. The test sensor forms at least one aperture therein. At least a portion of the at least one aperture is adjacent to the at least one reservoir. The assembly further comprises a hydrogel composition positioned on the test sensor. The hydrogel composition is linked to the at least one reservoir via the at least one aperture.

CLAIM OF PRIORITY AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.12/086,238, which was filed on Jun. 9, 2008, as a U.S. National Phase ofInternational Application No. PCT/US2006/047803, which was filed on Dec.14, 2006, and claims the benefit of and priority to U.S. ProvisionalPatent Application No. 60/751,238, filed Dec. 16, 2005, all of which areincorporated herein by reference in their respective entireties.

TECHNICAL FIELD

The present invention relates generally to a transdermal test sensorassembly. More particularly, the invention relates to a transdermal testsensor assembly adapted to assist in determining a concentration of atleast one analyte, where the test sensor assembly has hydratingfeatures.

BACKGROUND

The quantitative determination of analytes in body fluids is of greatimportance in the diagnoses and maintenance of certain physiologicalabnormalities. For example, lactate, cholesterol, and bilirubin shouldbe monitored in certain individuals. In particular, determining glucosein body fluids is important to diabetic individuals who must frequentlycheck the glucose level in their body fluids to regulate the glucoseintake in their diets. The results of such tests may be used todetermine what, if any, insulin or other medication needs to beadministered. In one type of testing system, test sensors are used totest a fluid such as a sample of blood.

According to some existing techniques, a lancet may be used to pierce auser's skin to draw fluid (e.g., blood) from the user. This fluid isthen used with an instrument or meter to determine an analyte (e.g.,glucose) concentration. Piercing a user's skin each time an analyteconcentration reading is desired is an inconvenient and invasiveprocedure. Moreover, the procedure is undesirable because of theresulting pain and discomfort often experienced by a user.

One non-invasive method for obtaining a sample for determining ananalyte concentration involves using a transdermal sample of one or moreanalytes found in, for example, interstitial fluid (ISF). In thismethod, a transdermal test sensor is placed on a user's skin. Thetransdermal sensor typically includes a hydrogel composition tofacilitate the extraction of the analyte of interest from the ISF viathe user's skin to an analyte-testing instrument or meter. The hydrogelmust be sufficiently mechanically and thermally stable to provide arelatively static, reactive, and aqueous conduct between a dermalsampling site and an analyte-testing instrument.

One problem with existing transdermal test sensors relates to having ahydrogel that is sufficiently hydrated and can maintain such hydration.Inadequate hydration may be caused by exposure to the outsideenvironment and/or the lack of a hermetic seal between the skin and thetest sensor. The level of hydration of the hydrogel (e.g., solventcontent) generally decreases over time. If the level of hydration of thehydrogel falls below a certain level, the hydrogel may cease to provideintimate contact between the skin and the hydrogel and/or the hydrogeland the test sensor. Such intimate contact is necessary for accuratetesting results.

Thus, it would be desirable to have a transdermal test sensor thatassists in addressing one or more of the above disadvantages.

SUMMARY

According to one embodiment of the present disclosure, a transdermaltest sensor assembly adapted to determine an analyte concentration of afluid sample is disclosed. The assembly comprises a sensor supportincluding at least one reservoir adapted to hold a liquid. The assemblyfurther comprises a test sensor being coupled to the sensor support. Thetest sensor forms at least one aperture therein. At least a portion ofthe at least one aperture is adjacent to the at least one reservoir. Theassembly further comprises a hydrogel composition positioned on the testsensor. The hydrogel composition is linked to the at least one reservoirvia the at least one aperture.

According to another embodiment of the present disclosure, a transdermalanalyte-testing assembly adapted to determine an analyte concentrationof a sample is disclosed. The assembly comprises a sensor supportincluding at least one reservoir adapted to hold a liquid. The assemblyfurther comprises a test sensor being coupled to the sensor support. Thetest sensor forms at least one aperture therein. At least a portion ofthe at least one aperture is adjacent to the at least one reservoir. Theassembly further comprises a hydrogel composition being linked to the atleast one reservoir via the at least one aperture. The assembly furthercomprises an analyte-testing instrument coupled to the sensor support.The analyte-testing instrument is adapted to determine an analyteconcentration of a sample.

According to another embodiment of the present disclosure, anon-invasive method of determining a concentration of at least oneanalyte in a body fluid is disclosed. The method comprises the act ofproviding a transdermal test sensor assembly including a sensor support,a test sensor, and a hydrogel composition. The sensor support includesat least one reservoir. The at least one reservoir includes a liquid.The test sensor is coupled to the sensor support. The test sensor formsat least one aperture therein. At least a portion of the at least oneaperture is adjacent to the at least one reservoir. The hydrogelcomposition is linked to the at least one reservoir via the at least oneaperture. The method further comprises the act of contacting thetransdermal sensor to an area of skin such that the hydrogel compositionis positioned between the skin and the test sensor. The method furthercomprises coupling an analyte-testing instrument to the transdermal testsensor assembly. The method further comprises determining theconcentration of the analyte using the analyte-testing instrument.

The above summary is not intended to represent each embodiment, or everyaspect, of the present invention. Additional features and benefits ofthe present invention are apparent from the detailed description andfigures set forth below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a perspective view of a test sensor assembly according toone embodiment of the present invention.

FIG. 1 b is an exploded, perspective view of the test sensor assembly ofFIG. 1 a.

FIG. 2 is a perspective view of a test sensor assembly of the presentinvention being coupled to an analyte-testing instrument.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The present invention is directed to a transdermal test sensor assemblyadapted to assist in determining a concentration of at least oneanalyte. The transdermal test sensor assembly has hydrating features.

Transdermal test sensors contain a hydrogel composition, which may serveas an interface between the sensor and the skin. A hydrogel compositionis defined herein as a cross-linked polymer gel. The hydrogelcomposition generally comprises at least one monomer and a solvent. Thesolvent is typically substantially biocompatible with the skin.Non-limiting examples of solvents that may be used in the hydrogelcomposition include water and a water mixture. The amount of solvent inthe hydrogel is generally between about 10 to about 95 weight percentand may vary depending on the monomer amount, crosslinking, and/or thedesired composition of the gel.

The transdermal test sensor assists in determining the concentration ofthe desired analyte by using the hydrogel as an osmotic agent to extractthe analyte from a fluid such as ISF. Analytes that may be measuredinclude glucose, lipid profiles (e.g., cholesterol, triglycerides, LDL,and HDL), fructose, lactate, and/or bilirubin. It is contemplated thatother analyte concentrations may be determined. One non-limiting exampleof the transdermal sensor's use is to determine the glucoseconcentration in a user's ISF.

In the embodiment of FIGS. 1 a,b, a transdermal test sensor assembly 10is illustrated according to one embodiment of the present invention.Although in this embodiment, the test sensor is an electrochemicalsensor, it is contemplated that the present invention may also beapplied to other sensors (e.g., optical test sensors). An example of anelectrochemical sensor includes a standard, three-electrode designutilizing a catalytic, platinum-containing working electrode, a counterelectrode, and a reference electrode. It is contemplated that otherelectrochemical sensors may be used including those with fewerelectrodes such as a two-electrode electrochemical sensor, whichincludes a counter electrode and a working electrode.

The test sensor assembly 10 includes a sensor support 12 and a testsensor 14. The test sensor 14 is positioned generally parallel andadjacent to the sensor support 12. The sensor support 12 of FIGS. 1 a,bincludes a recessed area 16 having dimensions generally similar to thedimensions of the test sensor 14. It is desirable for the recessed area16 to have dimensions substantially similar to the dimensions of thetest sensor 14 to inhibit movement of the test sensor 14 relative to thesensor support 12. It is contemplated that the test sensor assembly ofthe present invention may include a mechanism to further inhibitmovement of the test sensor 14 relative to the sensor support 12. Forexample, the test sensor 14 of FIGS. 1 a,b includes a flexible element18 a that may be adapted to attach to a corresponding curved element 18b of the sensor support 12. It is contemplated that other mechanismssuitable for inhibiting movement of the test sensor 14 with respect tothe sensor support 12 may also be used. For example, an adhesive may bepositioned between the sensor 14 and the sensor support 12.Alternatively, the sensor support 12 may include plastic molded pinsextending from the recessed area 16 through corresponding holes in thetest sensor 14. The pins may be, for example, heat-staked or sonicwelded to maintain the sensor 14 in place.

An outwardly-facing surface 20 of the test sensor 14 includes a hydrogelcomposition 22 a,b. Although in the illustrated embodiment, the hydrogel22 a,b is generally circular in shape, it is contemplated that thehydrogel 22 a,b may be of any shape. Moreover, although two hydrogelcompositions 22 a,b are illustrated, it is contemplated that any numberof hydrogel compositions 22 a,b may be included on the surface 20 oftest sensor 14. The hydrogel 22 a,b generally has a thickness of fromabout 0.05 mm to about 5 mm and, more specifically, has a thickness offrom about 0.01 mm to about 1 mm. The surface area of the test sensor 14covered by the hydrogel 22 a,b in one embodiment is from about 0.1 cm²to about 100 cm². The hydrogel 22 a,b is generally positioned over aplurality of electrodes 23. The plurality of electrodes 23 includes acounter electrode, a reference electrode, and a working (measuring)electrode. It is contemplated that other electrode structures may beused.

In the embodiments of FIGS. 1 a,b and 2, the test sensor 14 is adual-sensor test sensor, wherein each of two sensors 27 a,b isindependent of the other. The test sensor assembly 10 includes twocorresponding reservoirs 24 a,b (see FIG. 1 b). It is contemplated thata different number of sensors 27 and corresponding reservoirs 24 may beused with the present invention.

The reservoirs 24 a,b of the illustrated embodiment are located withinthe recessed area 16. The reservoirs 24 a,b are adapted to store aliquid 26 for hydrating the hydrogel composition 22 a,b. The types ofliquid that may be stored in the reservoirs 24 a,b include a secondhydrogel, a solvent, or the like. The solvent may be the same as ordifferent from the solvent used in the hydrogel composition 22 a,b.Although in the illustrated embodiment of FIG. 1 b, the reservoirs 24a,b have a generally round shape, it is contemplated that the reservoirs24 a,b may have other shapes.

The test sensor 14 includes at least one aperture 28 a,b per sensor 27a,b formed therein that is positioned generally below the hydrogel 22a,b and generally above the reservoir 24 a,b, as shown in FIGS. 1 a,b.The at least one aperture 28 a,b serves as a conduit for the liquid 26and the hydrogel 22 a,b. Thus, as the hydration of the hydrogel 22 a,bbegins to decrease, the liquid 26 in the reservoir 24 a,b suppliesadditional hydration to the hydrogel 22 a,b. It is desirable for theliquid 26 to generally include a greater percent of solvent than thehydrogel 22 a,b so that the hydrogel 22 a,b may more readily absorb theliquid 26. The hydrogel 22 a,b may become saturated at a certain pointat which it will no longer be able to absorb the liquid 26. By reducingor substantially eliminating dehydration of the hydrogel 22 a,b, thetransport properties of the hydrogel 22 a,b are not altered, and moreaccurate testing results may be obtained.

The test sensor assembly of the present invention may be coupled to ananalyte-testing instrument, or meter, as shown in the embodiment of FIG.2. Referring to FIG. 2, a meter assembly 100 includes a test sensorassembly 110 coupled to a meter 111. The test sensor assembly 110 ofFIG. 2 is substantially similar to the test sensor assembly 10 of FIGS.1 a,b and described above. In the illustrated embodiment, the meter 111is coupled to a surface of a sensor support 112 opposite a test sensor114. It is contemplated that the meter 111 may be coupled to otherportions of the test sensor assembly 110. It is contemplated that anymechanism suitable for maintaining the test sensor assembly 110 and themeter 111 in a substantially fixed position may be used including, butnot limited to, snaps, screws, or other fasteners. The meter 111 isadapted to determine the concentration of the desired analyte in a fluidsample such as an ISF sample.

To test an analyte (e.g., glucose) concentration in an ISF sample, ahydrogel composition 128 a,b on the test sensor 114 is placed against auser's skin, thereby coupling the skin and the test sensor 114. The testsensor assembly 110 may be applied at a skin site such as the volarforearm between the wrist and elbow such that the hydrogel 122 a,b ispositioned generally between the skin site and the test sensor 114. Itis contemplated that the test sensor assembly 110 may be applied atother skin sites such as the abdomen. It is contemplated that the meter111 and/or the test sensor assembly 110 may be used for continualglucose monitoring or for non-continual glucose monitoring.

It may be desirable for the skin to be pre-treated to increase the skinpermeability prior to applying the test sensor assembly 110. One exampleof pre-treating is to use ultrasound energy to disrupt the lipid bilayerof the stratum corneum so as to increase the skin permeability. Byincreasing the skin permeability, the amount of ISF used in transdermalsampling is increased. This results in improved sampling of the analytesof interest found in the ISF.

One non-limiting source of an ultrasound energy system is SontraSonoPrep® ultrasonic skin permeation system marketed by Sontra MedicalCorporation (Franklin, Mass.). The SonoPrep® system applies relativelylow frequency ultrasonic energy to the skin for a limited duration (fromabout 10 to 20 seconds). The ultrasonic horn contained in the devicevibrates at about 55,000 times per second (55 KHz) and applies energy tothe skin through the liquid-coupling medium to create cavitation bubblesthat expand and contract in the coupling medium.

Referring again to FIG. 2, according to one method, the meter assembly100 is used for continual, transdermal monitoring of an analyte (e.g.,glucose). In a continual monitoring system, the meter assembly 100measures an analyte concentration (e.g., glucose) at regular intervals,which may range from milliseconds to minutes. Because the meter 100 mayremain coupled to the sensor support 112 for extended periods of time,it is desirable that the meter 113 be of a compact size to minimize thebulkiness and inconvenience to a user. The meter 100 may also be adaptedto wirelessly transmit testing data to, for example, a remote computerdata management system 130.

As discussed above, the hydrogel generally includes a monomer(s) and asolvent. In addition to a monomer and solvent, it is contemplated thatthe hydrogel composition may include other materials. For example, anelectrolyte may be added to the hydrogel composition. The electrolytedesirably contains a high salt concentration that assists in exertingosmotic pressure on the skin. By exerting osmotic pressure on the skin,the electrolyte assists in driving out the ISF that contains theanalyte. Non-limiting examples of electrolytes that may be used includesodium and potassium salts of chloride, phosphate, citrate, acetate, andlactate.

The hydrogel composition may further include a liquid. The liquid mayinclude electrolytes. The concentration of electrolytes in the liquid isgenerally high enough to ensure the functionality of the process ofdetermining an analyte concentration, yet low enough that the liquidremains hypotonic relative to the body fluid being tested (e.g., ISF).The electrolytes may cause a diffusional driving force of numeroussolutes into the hypotonic liquid. The driving force may also enhancethe transport of analyte (e.g., glucose) toward the sensor surface.Alternatively or additionally, the liquid may include a composition forgenerally increasing the efficiency of reactions involved in the processof determining the analyte concentration. For example, the liquid mayinclude a buffer having a pH level conducive for the glucose oxidaseconversion of glucose in the hydrogel.

The hydrogel composition may further include an enzyme to assist indetermining the analyte concentration. Depending on the analyte, anenzyme may assist in converting the analyte into a species amenable todetection, such as electrochemical detection. One example of an enzymethat may be used in determining glucose is glucose oxidase. It iscontemplated that other enzymes may be used, such as glucosedehydrogenase. If other analytes are of interest, an appropriatelyselected enzyme may assist in determining the concentration of thatanalyte.

The hydrogel composition may further include a permeation enhancer.Permeation enhancers are desirable in applications in which the hydrogelcomposition is applied to the skin. The permeation enhancer assists inopening up pores of the skin. Non-limiting examples of permeationenhancers that may be used include, but are not limited to, squalene,unsaturated fatty acids, glycerol derivatives of fatty alcohols,dimethylsulfoxide, and alkyl esters of fatty acids.

Other materials that may be added to the hydrogel composition include,but are not limited to, biocides, humectants, surfactants, andcombinations thereof. Biocides assist in exhibiting bacterial growth.Non-limiting examples of biocides that may be used include the Parabenseries of preservatives, sodium benzoate, benzalkonium chloride, andtrialkyl amines. Humectants assist in applications in which it isdesirable to keep the skin moist. Non-limiting examples of humectantsthat may be used include glycerol, hexylene glycol and sorbitol,maltitol, polydextrose, propylene glycol, lactic acid, and lactate metalsalts. Surfactants assist in coupling the hydrogel composition with theskin to obtain an improved contact therebetween. Non-limiting examplesof surfactants that may be used include alkyl phenols such as TRITON®X-100 (octyl phenol ethoxylate having a molecular formula ofC₁₄H₂₂O(C₂H₄O)_(n) in which an average “n” is 9 or 10), and sorbitol andsorbitol derivatives such as the TWEEN™ series.

The hydrogel composition desirably possesses sufficient mechanical andthermal stability to provide a relatively static, reactive, and aqueousconduit between the dermal sampling site and the sensor. Morespecifically, it is desirable for the hydrogel composition to havephysical uniformity and flexibility, and mechanical stability againstshear force. It is also desirable for the hydrogel composition tomaintain the porosity of the skin. The hydrogel composition alsodesirably displays a relatively high degree of compressibility to assistin securing good skin/sensor connectivity or skin adhesiveness.

It is also desirable for the hydrogel composition to have porosity largeenough for enzyme entrapment. For example, in some applicationsinvolving the determination of glucose concentration, it is desirablefor the hydrogel composition to provide a matrix for glucose oxidase anda diffusion passage for glucose and hydrogen peroxide.

A hydrogel that may be used with the present invention may comprise afirst monomer, a second monomer, a cross-linking agent, and a solvent.The first monomer is selected from the group consisting of N-vinylpyrrolidone, hydroxy alkyl methacrylates, acrylamide, and N,N di-alkylacrylamides. The second monomer is selected from the group consisting ofalkyl (meth)acrylates, N-vinyl acylamide, vinyl esters, and vinylethers. The ratio of the first monomer to the second monomer is fromabout 0.1:99.9 to about 99.9:0.1.

One example of a hydrogel that may be used comprises N-vinyl pyrrolidoneas a first monomer and vinyl acetate as a second monomer. The hydrogelfurther comprises a photo-initiator(2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone) marketed asIrgacure® 2959 by Ciba Specialty Chemicals Pty Ltd., and a cross-linkingagent (diethylene glycol divinyl ether). The copolymeric mixtureincludes 50 parts N-vinyl pyrrolidone, 50 parts vinyl acetate, 0.5 partsIrgacure® 2959, and 0.5 parts diethylene glycol divinyl ether.

Alternative Embodiment A

A transdermal test sensor assembly adapted to determine an analyteconcentration of a fluid sample, the test sensor assembly comprising:

a sensor support including at least one reservoir adapted to hold aliquid;

a test sensor being coupled to the sensor support, the test sensorforming at least one aperture therein, at least a portion of the atleast one aperture being adjacent to the at least one reservoir; and

a hydrogel composition positioned on the test sensor, the hydrogelcomposition being linked to the at least one reservoir via the at leastone aperture.

Alternative Embodiment B

The assembly of Alternative Embodiment A, wherein the at least onereservoir further includes a liquid.

Alternative Embodiment C

The assembly of Alternative Embodiment B, wherein the hydrogel includesa solvent, the liquid of the at least one reservoir includes a solvent,the solvent percentage of the liquid being greater than the solventpercentage of the hydrogel.

Alternative Embodiment D

The assembly of Alternative Embodiment A, wherein the sensor supportfurther includes a recessed area having dimensions generally similar todimensions of the test sensor, the recessed area being adjacent to thetest sensor, the at least one reservoir being positioned within therecessed area.

Alternative Embodiment E

The assembly of Alternative Embodiment A, wherein the assembly furthercomprises a coupling mechanism for coupling the test sensor assembly toan analyte-testing instrument.

Alternative Embodiment F

The assembly of Alternative Embodiment A, wherein the hydrogelcomposition comprises at least one monomer and a solvent.

Alternative Embodiment G

A transdermal analyte-testing assembly adapted to determine an analyteconcentration of a sample, the analyte-testing assembly comprising:

a sensor support including at least one reservoir adapted to hold aliquid;

a test sensor being coupled to the sensor support, the test sensorforming at least one aperture therein, at least a portion of the atleast one aperture being adjacent to the at least one reservoir;

a hydrogel composition being linked to the at least one reservoir viathe at least one aperture; and

an analyte-testing instrument coupled to the sensor support, theanalyte-testing instrument being adapted to determine an analyteconcentration of a sample.

Alternative Embodiment H

The assembly of Alternative Embodiment G, wherein the at least onereservoir further includes a liquid.

Alternative Embodiment I

The assembly of Alternative Embodiment G, wherein the hydrogel includesa solvent, the liquid of the at least one reservoir includes a solvent,the solvent percentage of the liquid being greater than the solventpercentage of the hydrogel.

Alternative Embodiment J

The assembly of Alternative Embodiment G, wherein the sensor supportfurther includes a recessed area having dimensions generally similar todimensions of the test sensor, the recessed area being adjacent to thetest sensor, the at least one reservoir being positioned within therecessed area.

Alternative Embodiment K

The assembly of Alternative Embodiment G, wherein the hydrogelcomposition comprises at least one monomer and a solvent.

Alternative Embodiment L

The assembly of Alternative Embodiment G, wherein the analyte-testinginstrument is adapted to determine the analyte concentration atpre-selected time intervals.

Alternative Process M

A non-invasive method of determining a concentration of at least oneanalyte in a body fluid, the method comprising the acts of:

providing a transdermal test sensor assembly including a sensor support,a test sensor, and a hydrogel composition, the test sensor supportincluding at least one reservoir, the at least one reservoir including aliquid, the test sensor being coupled to the sensor support, the testsensor forming at least one aperture therein, at least a portion of theat least one aperture being adjacent to the at least one reservoir, thehydrogel composition being linked to the at least one reservoir via theat least one aperture;

contacting the transdermal sensor to an area of skin such that thehydrogel composition is positioned between the skin and the test sensor;

coupling an analyte-testing instrument to the transdermal test sensorassembly; and

determining the concentration of the analyte using the analyte-testinginstrument.

Alternative Process N

The method of Alternative Process M, wherein the area of skin ispre-treated.

Alternative Process O

The method of Alternative Process M, wherein the act of determining theconcentration of the analyte using the analyte-testing instrument isrepeated at pre-selected time intervals.

Alternative Process P

The method of Alternative Process M, wherein the hydrogel includes asolvent, the liquid of the at least one reservoir includes a solvent,the solvent percentage of the liquid being greater than the solventpercentage of the hydrogel.

Alternative Process Q

The method of Alternative Process M, wherein the sensor support furtherincludes a recessed area having dimensions generally similar todimensions of the test sensor, the recessed area being adjacent to thetest sensor, the at least one reservoir being positioned within therecessed area.

Alternative Process R

The method of Alternative Process M, wherein the hydrogel compositioncomprises at least one monomer and a solvent.

While the invention is susceptible to various modifications andalternative forms, specific embodiments and methods thereof have beenshown by way of example in the drawings and are described in detailherein. It should be understood, however, that it is not intended tolimit the invention to the particular forms or methods disclosed, but,to the contrary, the intention is to cover all modifications,equivalents and alternatives falling within the spirit and scope of theinvention as defined by the appended claims.

1. A test sensor assembly for determining a concentration of an analytein a fluid sample, the test sensor assembly comprising: a sensor supportincluding at least one reservoir configured to hold liquid; a testsensor coupled to the sensor support, the test sensor forming at leastone aperture therein, at least a portion of the at least one aperturebeing proximal to the at least one reservoir; and a hydrogel compositionpositioned on the test sensor, the hydrogel composition being linked tothe at least one reservoir via the at least one aperture.
 2. The testsensor assembly of claim 1, wherein the sensor support further includesa recessed area within which is seated the test sensor, the recessedarea having dimensions similar to dimensions of the test sensor suchthat the recessed area inhibits movement of the test sensor relative tothe sensor support.
 3. The test sensor assembly of claim 1, wherein thetest sensor includes a plurality of electrodes, the hydrogel compositionbeing positioned over the plurality of electrodes.
 4. The test sensorassembly of claim 1, further comprising a liquid in the at least onereservoir, wherein the liquid hydrates the hydrogel composition.
 5. Thetest sensor assembly of claim 1, further comprising a liquid in the atleast one reservoir, wherein the hydrogel composition includes a firstpercentage of a solvent, and the liquid includes a second percentage ofa solvent, the second solvent percentage of the liquid being greaterthan the first solvent percentage of the hydrogel.
 6. The test sensorassembly of claim 1, wherein the test sensor further comprises aflexible coupling mechanism coupling the test sensor to the sensorsupport.
 7. The test sensor assembly of claim 1, wherein the sensorsupport is configured to mechanically couple to a meter and the testsensor is configured to electrically couple to the meter.
 8. The testsensor assembly of claim 1, wherein the hydrogel composition comprisesat least one monomer and a solvent.
 9. A transdermal analyte-testingassembly for determining an analyte concentration in a sample, thetransdermal analyte-testing assembly comprising: a sensor supportincluding at least one reservoir configured to hold liquid; a testsensor coupled to the sensor support, the test sensor forming at leastone aperture therein, at least a portion of the at least one aperturebeing proximal to the at least one reservoir; a hydrogel compositionfluidly coupled to the at least one reservoir via the at least oneaperture; and an analyte-testing instrument coupled to the sensorsupport, the analyte-testing instrument being operable to determine theanalyte concentration of the sample.
 10. The transdermal analyte-testingassembly of claim 9, further comprising a liquid in the at least onereservoir, wherein the liquid hydrates the hydrogel composition throughthe at least one aperture.
 11. The transdermal analyte-testing assemblyof claim 9, further comprising a liquid in the at least one reservoir,wherein the hydrogel composition includes a first percentage of asolvent, and the liquid includes a second percentage of a solvent, thesecond solvent percentage of the liquid being greater than the firstsolvent percentage of the hydrogel.
 12. The transdermal analyte-testingassembly of claim 9, wherein the sensor support further includes arecessed area having dimensions generally similar to dimensions of thetest sensor, the recessed area being adjacent to the test sensor, the atleast one reservoir being positioned within the recessed area.
 13. Thetransdermal analyte-testing assembly of claim 9, wherein the hydrogelcomposition comprises at least one monomer and a solvent.
 14. Thetransdermal analyte-testing assembly of claim 9, wherein theanalyte-testing instrument is adapted to determine the analyteconcentration at pre-selected time intervals.
 15. A method ofdetermining a concentration of at least one analyte in a body fluid, themethod comprising: providing a transdermal test sensor assemblyincluding a sensor support, a test sensor, and a hydrogel composition,the test sensor support including at least one reservoir, the at leastone reservoir including a liquid, the test sensor being coupled to thesensor support, the test sensor forming at least one aperturetherethrough, at least a portion of the at least one aperture beingproximal to the at least one reservoir, the hydrogel composition beingfluidly coupled to the at least one reservoir via the at least oneaperture; contacting the transdermal sensor to an area of skin such thatthe hydrogel composition is positioned between the skin and the testsensor; coupling an analyte-testing instrument to the transdermal testsensor assembly; and determining the concentration of the analyte usingthe analyte-testing instrument.
 16. The method of claim 15, furthercomprising pretreating the area of skin to thereby increase thepermeability of the area of skin.
 17. The method of claim 15, whereinthe determining the concentration of the analyte using theanalyte-testing instrument is repeated at pre-selected time intervals.18. The method of claim 15, wherein the hydrogel includes a firstpercentage of a solvent, the liquid of the at least one reservoirincludes a second percentage of a solvent, the second solvent percentageof the liquid being greater than the first solvent percentage of thehydrogel.
 19. The method of claim 15, wherein the sensor support furtherincludes a recessed area having dimensions generally similar todimensions of the test sensor, the recessed area being adjacent to thetest sensor, the at least one reservoir being positioned within therecessed area.
 20. The method of claim 15, wherein the hydrogelcomposition comprises at least one monomer and a solvent.